1. Field of the Invention
This invention relates to semiconductor manufacturing techniques. Specifically, the present invention relates to reinforced attachment of a leadframe to a substrate.
2. Prior Art
Leadframes are commonly attached to substrates to form a leadframe/substrate assembly. Often, the leadframe is attached to the substrate with the smaller inner tips of the bonding fingers attached to the substrate. An integrated-circuit die is then attached to the substrate within the central opening contained within the leadframe. Bonding pads on the integrated-circuit die are electrically connected to respective bonding fingers to form a semiconductor assembly.
However, during subsequent handling of the leadframe, the bonding fingers of the leadframe may lift or detach from the substrate. If such detachment occurs the reliability of the semiconductor assembly is severely degraded. The degradation of reliability may occur as a result of compromised electrical connection between the integrated-circuit die and the detached bonding fingers, shorting due to contact between the detached bonding fingers and adjacent bonding fingers, or for numerous other reasons.
Additionally, the problem of bonding finger detachment from the substrate is compounded as ultra-fine pitch leadframes are developed. That is, with even greater numbers of bonding fingers per leadframe and with the bonding fingers become correspondingly smaller or thinner, the integrity of the attachment of the leadframe bonding fingers to the substrate is of greater concern.
In seeking to reinforce the leadframe to substrate attachment, it is desired to keep the cost of the assembly to a minimum, and insure that any reinforcement means are compatible with standard subsequent processing steps.
Thus, the need has arisen for means to reinforce leadframe to substrate attachment which does not substantially increase the cost of the assembly and which is compatible with standard subsequent processing steps.